Pachyopella flavida ( Wiedemann, 1824 )

Soares, Matheus M. M., Gaimari, Stephen D., Corrêa-Neto, José De J., Limeira-De-Oliveira, Francisco & Rafael, José A., 2024, Insect (Hexapoda) diversity in the oceanic archipelago of Fernando de Noronha, Brazil: Lauxaniidae (Diptera), Zootaxa 5537 (1), pp. 1-23 : 7-11

Pachyopella flavida ( Wiedemann, 1824)

( Figs. 3 , 4 )

Lauxania flavida Wiedemann, 1824: 57 . Type locality: South America. Syntype male, Natural History Museum of Denmark, Copenhagen (examined SDG).

Diagnosis. Easily recognized by the elongated first flagellomere, about 8X longer than high ( Fig. 3A–D ); face yellow, with a rounded dark brown spot at middle ( Fig. 3C ); ocellar triangle in front of inner vertical seta ( Fig. 3E ); anterior dorsocentral seta strong, close to suture; surstylus elongated, about 4X longer than wide, somewhat finger-shaped ( Fig. 4A, B ).

Redescription. Head ( Figs. 3A–E ). Mostly orangish yellow, except dark brown surrounding ocellar triangle and with a small, rounded dark brown spot on face; 1.2X higher than long, 1.4X wider than high, 1.2X wider than scutum; eye 1.2X higher than long; gena height (directly below eye) 0.2X eye height. Vertex shiny, rounded; inner vertical seta long and strong, about 2X longer than outer vertical seta, with distance between them about 1/2 that from inner vertical seta to central vertex. Ocellar triangle small, slightly raised, placed slightly in front of vertex, in front of level of inner vertical seta; ocelli subequal in size, arranged in small equilateral triangle, covered with few tiny setulae, with 2–3 pairs of setulae between the ocellar triangle and vertex. Ocellar setae proclinate and slightly divergent, subequal in length to outer vertical seta. Postocellar setae cruciate, slightly shorter than ocellar seta. One row of short postocular setulae. Median occipital sclerite with supracervical setae above occipital foramen. Frons 2X wider than long, flat, at a distinct obtuse angle with facial plane; with 2 strong fronto-orbital setae, posterior seta reclinate, about 2X longer than anterior seta, located at midpoint between inner vertical seta and lunule; anterior seta inclinate, located at midpoint between posterior seta and lunule; frons setulose at anterior corners and between the anterior and posterior fronto-orbital setae. Lunule low, straight; gap between antennae greater than diameter of one antennal base, antennal base slightly bulging. Antenna mostly dark brown, except scape brownish orange, pedicel orange, dorsal 1/4 of first flagellomere pale orange, and arista pale yellow; scape with short setulae on dorsal surface; pedicel with 1 long dorsal seta at middle length, with crown of short setulae at apex and 3–4 long ventral setae; first flagellomere about 8X longer than high, and about 4X longer than scape and pedicel combined, with rounded apex; arista shorter than first flagellomere and inserted at its base, plumose, with upper rays longer than lower, and rays decreasing in length towards apex. Gena with row of long and sparse setae at ventral edge, extended above middle of parafacial; postgena pale yellow, with few short and sparse setae. Face about 1.3X wider than high, face slightly bulging, concave at lower margin; parafacial silvery pruinose, wide, about 1/3 width of face. Clypeus orange, narrow. Maxillary palpus orangish yellow basally and dark brown apically, clavate, with long setae at apex; labellum orangish yellow.

Thorax ( Fig. 3A, B, E ). Scutum slightly arched, about 1.2X longer than wide; scutellum about 1/3 as long as scutum, with width at base about 1.6X greater than length; scutum mostly homogeneously orangish-yellow, postpronotum pale yellow; scutellum and pleural region pale yellow. Chaetotaxy: 0+3 dorsocentral setae, anterior seta short, about 1/2 as long as middle seta, located close to transverse suture, middle seta located at midpoint between posterior seta and transverse suture, posterior seta strongest, located near midpoint between scutellar suture and middle seta; prescutellar acrostichal seta present, weaker than anterior dorsocentral seta; 1 postpronotal seta; 2 notopleural setae, in anterior and posterior corners, anterior seta slightly longer than posterior; postsutural intra-alar seta absent; 1 presutural and 1 postsutural supra-alar setae; 2 postalar setae, in anterior and posterior corners; 6 regular rows of acrostichal setulae extending posteriorly to level of middle dorsocentral seta, only 2 rows between middle and posterior dorsocentral setae; row of setulae present along dorsocentral area, and setulose outside dorsocentral row; proepisternal seta present, slender; anepisternal seta along posterior edge of anepisternum, anepisternum sparsely setulose in posterior 2/3; anepimeron bare; 1 katepisternal seta present, katepisternum otherwise with several smaller setulae anterior of seta, and with 2–3 long ventral setae, close to the coxa; 2 pairs scutellar setae, anterior setae subparallel, posterior setae slightly convergent. Legs ( Fig. 3A, B ). Pale yellow, slightly darker on fore tarsomeres. Fore femur with 3 long and strong posteroventral setae at apical 1/2, about 1.3X longer than width of femur, posterior row of setae from base to apical 2/3, shorter and thinner than posteroventral setae; ctenidium absent. Mid femur with anterior row of short and strong setae in apical 1/2, and with 1 short curved posteroventral preapical seta. Hind femur with anteroventral row of short setae at apical 1/3 and 2–3 anterodorsal longer setae. All tibiae with preapical dorsal seta, strongest on mid tibia; mid tibia with 1 longer preapical ventral seta, as long as dorsal seta; hind tibia with 1 short apical ventral spur. Wing ( Fig. 3F ). Hyaline; sapromyziform; veins pale brown. Length 3.0 mm; 2.8X longer than high. Cell dm about 4X longer than crossvein dm-m. Crossvein r-m located at midpoint of cell dm. Vein R 4+5 ending at wing tip, subparallel with veins R 2+3 and M 1. Crossvein dm-m straight, located slightly basal to midpoint between crossvein r-m and tip of vein M 1. Vein M 4 about 0.6X as long as crossvein dm-m. Vein CuA+CuP short, about 1/3 as long as vein A 1.

Abdomen ( Fig.3A ).Homogeneously orangish-yellow,tapered gradually after segment3.Tergites homogeneously covered with short setulae, longest and strongest along posterior edges of syntergite 1+2 and tergites 3–5. Sternites pale yellow to white, sternite 1 bare, sternites 2–5 with sparse fine setae, slightly longer at lateral edges; sternites 2–5 each slightly longer than wide, subequal in width sternite to sternite; sternite 6 a membranous transverse strip. Male genitalia ( Figs. 3G , 4A–E ). Yellow. Syntergosternite 7+8 simple, bare, transversely saddle-shaped. Epandrium simple, saddle-shaped; with long setae along posterior edge, 2X longer than widest point ( Fig. 4A, B ). Surstylus elongated, about 4X longer than wide, somewhat finger-shaped, slightly shorter than epandrium, with sparse short setulae ( Fig. 4A, B ). Subepandrial sclerite subrectangular, about 2X wider than long, weakly sclerotized. Cercus simple, small, ovoid, densely setose ( Fig. 4A, B ). Ejaculatory apodeme short and narrowed anteriorly. Phallus apically projected posteriorly, truncated at apex, about 2.5X longer than wide, phallus with a median constriction, and widened before apex in posterior view; opening of distiphallus with short, sclerotized teeth ( Fig. 4C, D ). Hypandrium as a narrow transverse stripe, with 2 long setae close to the postgonite. Pregonite absent. Postgonite short and subrectangular in lateral view ( Fig. 4C ), pointed and somewhat subtriangular in posterior view ( Fig. 4D ).

Female: Similar to male ( Fig. 3B ). Female terminalia ( Fig. 4F–H ). Tergite 7 not fused to sternite 7. Tergite 8 almost entirely membranous, with 2–3 irregular rows of short setae at posterior edge ( Fig. 4E, F ). Sternite 8 somewhat rectangular, setulose, with large membranous median area, almost splitting the sternite ( Fig. 4G ). Epiproct semicircular, setulose, with row of strong setae at posterior edge ( Fig. 4E, F ). Hypoproct narrow, semicircular, heavily setulose ( Fig. 4E, G ). Spermathecae round, with configuration 1+2, paired spermathecae, surface smooth ( Fig. 4H ).

Material examined. BRAZIL, Pernambuco, Fernando de Noronha: Açude Xaréu , 03°51′30″S – 32°25′50″W, 01–09.vi.2019, varredura [sweeping], J.A. Rafael, F. Limeira-de-Oliveira & D.M.M. Mendes (2 ♀, INPA) ; Capim-açu , 03°51′17″S – 32°26′26″W, 09–24.vi.2019, large Malaise trap, J.A. Rafael, F. Limeira-de-Oliveira & L.C. Castro (2 ♂, 38 ♀, INPA; 1 ♂, 3 ♀, AMNH; 3 ♀, CSCA; 1 ♂, 3 ♀, USNM, 1 ♂, 3 ♀, SDG) ; Ilha Rata , 03°48′54″S 32°23′19″W, 01–09.vi.2019, varredura [sweeping], J.A. Rafael & D.M.M. Mendes (1 ♀, INPA) ; Sueste Mangue , 03°51′30″S – 32°25′50″W, 01–09.vi.2019, arm. luz [light trap], J.A. Rafael, F. Limeira-de-Oliveira & D.M.M. Mendes (1 ♀, INPA) ; Trilha Sancho , 3°51′30″S – 32°25′50″W, 01–09.vi.2019, Malaise trap, J.A. Rafael, F. Limeira-de-Oliveira & D.M.M. Mendes (3 ♂, 2 dissected, 25 ♀, INPA) ; same data, except fezes humana [human feces] (1 ♀, INPA) . Additionally, 1798 specimens from nearly all localities and dates pinned and in ethanol.

Remarks. This species can be easily recognized among the lauxaniid species occurring in Fernando de Noronha by the long first flagellomere, about 8X longer than high. Pachyopella flavida is a widespread species, occurring from the southeastern United States (Florida) to Northern Argentina ( Gaimari & Silva 2020) . It was recorded only recently from Fernando de Noronha as Pachyopella cf. flavida based on more than 300 specimens. After nine months we collected 1886 specimens in Fernando de Noronha, 568 being in Capim-Açu, 1049 in Sancho and 269 in other localities of the archipelago, including one specimen from Ilha Rata. Pachyopella flavida was the second more abundant species in Fernando de Noronha, representing 10% of the specimens collected throughout the nine months using interception traps.

Distribution. Widespread throughout Central America and most of South America, and present in the southeastern United States (Florida).

Discussion. The genus Pachyopella comprises four described species, with this species being the most widespread. The other three are from Paraguay, Jamaica, and Central America. Although no biological information is known for any species of the genus, Broadhead (1984) discusses the adult mouthpart morphology adaptations for fungal grazing in one species. No immature stages are known for this genus.

Figures

FIGURE 3. Pachyopella flavida (Wiedemann, 1824). A, C–G male (INPA), B female (INPA). A, B. Habitus, lateral view; C, D. Head anterior and lateral views, respectively; E. Head and thorax, dorsal view; F. Wing; G. Male terminalia, posterior view. Abbreviations: afrs = anterior fronto-orbital seta; ep = epandrium; kpt s = katepisternal seta; flgm 1 = first flagellomere; ot = ocellar triangle.

FIGURE 4. Pachyopella flavida (Wiedemann, 1824). A–D male (INPA), E–H female (INPA). A, B. Epandrium in posterior and lateral views, respectively; C, D. Internal appendages in lateral and anterior views, respectively; E–G. Female terminalia in lateral, dorsal and ventral views, respectively; H. Spermathecae. Abbreviations: bp = basiphallus; cerc = cercus; e = epiproct; epand = epandrium; h = hypoproct; hypd = hypandrium; ej apod = ejaculatory apodeme; te = teeth of distiphallus; st = sternite; tg = tergite; pgt = postgonite; sur = surstylus.